When you are getting an antenna short, satellite low or antenna fault alarm, there are a number of things to test in order to distinguish what is wrong and how to fix the issue.
When you disconnect the antenna connection from the unit, does the short alarm switch to a no alarm alert? If the alarm does not change, this could mean there is an issue in the unit. In this case an RMA will need be requested.
If the alarm does change to a no antenna error, the next thing to test will be testing the resistance between a number of different points.
First measure the resistance between the core of the antenna and the shield, this should form an open circuit.
Secondly test the resistance between the core and the shield of the lightning protector. This should also form an open circuit.
Third of all measure the resistance between the core and the shield of the lightning protector, this should form an open circuit.
Lastly measure the resistance between the core from both ends of the lightning protector. This should be a closed circuit.
If any of these are not the case there could be an issue with the antenna cable, to fix this consider replacing it.